Field separations:

Electrical field is generally used to affect separations and the different methods which are based on the application of this type of field are

i) Electrodeposition,

ii) Electrophoresis,

iii) Capillary electrophoresis and

iv) Electrochromatography.

The instances for separations resulting because of application of gravitational and thermal fields are ultracentrifugation and thermal diffusion, respectively.

After going through both types of classification, one can see that most of the known techniques are included in one or the other category. But it may be mentioned that the list of separation methods considered for classification is not exhaustive. A few of the lesser known methods have not been taken into consideration. The other point which has to be kept in mind is that in some of the methods, particularly chromatographic, more than one mechanism is operative and the method may be classified under different categories.